Preheat the oven to 425 degrees F. Brush a 9x13 inch baking dish with the melted butter.

In a small bowl, whisk together the egg and sourdough starter.

In a large bowl, whisk together the flour, baking powder and salt. Add in the butter and use a fork or pastry blender to work it into the flour, dispersing the small pieces throughout the mixture. Stir in the grated cheese and fresh herbs if using them.

Pour the buttermilk and the sourdough/egg mixture into the dry ingredients and mix until just combined. You can even use your hands to really bring it together. Press the mixture into the buttered baking dish. Use a knife to score the dough - basically pre-cutting the biscuits to make them easier to cut when finished.

To brown the butter, place the butter in a skillet over medium heat. Cook and let the mixture bubble, stirring occasionally, until brown bits begin to appear on the bottom. Once the brown bits appear, turn the heat off and continue to stir for about 30 seconds. Drizzle the top of the dough with the brown butter.

Bake for 30 to 35 minutes, until golden and puffed. Let cool (almost!) completely before cutting and serving.